Steering gear



July 13, 1948.- R. E. FARMER 2,445,263

- v STEERING GEAR Filed July 17,1946 2 Sheets-Sheet 1 R0) 5. FZRMERINVENTOR.

July 13, 1948. R E FARMR 2,445,263 I STEERING GEAR Filed July 17,1946 2Sheets-Sheet 2 ROY E. FARMER' INVENTOR.

Patented July 13, 1948 Roy E. Farmer, Detroit, Mich, assign'orto FordMotor Company, Dearborn; Micha, at. 00111011259 tion of Delaware 2Application July 1'7, 1946; Ser'iafNo. 684,3'il5'.

This-application is concerned with alvehicular steering gear and moreparticularly with a steering gear specifically adapted to agricuturaltractors and similar heavy duty apparatus in which steering isaccomplished by a steering wheel which is mounted in a vertical planethrough the transverse midsection of the tractor.

Heretofore tractors have been steered through this type of centrallylocated gear with the output from the steering gear taken oif on eitheror both sides of the gear box. Where the output has been taken off onlyon one side, the remainder of the steering mechanism has closelyfollowed automotive practice and made use of the conventional tie rodfor connecting the two front wheels. Where the output has been taken offfrom both sides of the gear box through two individual steering arms, aseparate drag link has been provided for each front wheel. It is thislatter type of double take off steering gear with which this applicationis concerned.

In this double take off type of steering gear it has been heretoforedeemed necessary, in order to maintain proper steering symmetry, to havethe two take off shafts leading from the gear box coaxial. The use of asolid shaft extending through the gear box is precluded since therotation of the left take off shaft is of necessity opposite indirection to that of the right hand take off shaft. In practice theserequirements that the two take off shafts be coaxial and revolve inopposite directions, have led to some rather bulky, complicated andexpensive structures. Applicant has discovered that proper steeringgeometry can be maintaianed even though the two take off shafts do notpresent coincident axes, and has invented a simple, rugged andinexpensive steering gear in which this discovery can be utilized.Applicants preferred structure is composed largely of parts longstandard in automotive steering apparatus.

Accordingly it is an object of this invention to provide a vehicularsteering gear having two take offs whose axes are non-coincident.

It is a further object of this invention to provide a tractor steeringgear having two eccentric take offs and which utilizes to a large degreeparts standard in automotive practice.

With these and other objects in view, the invention consists in thearrangement, construction and combination of the various parts of theimproved structure as described in the specification, claimed in theclaim and illustrated in the accompanying drawings, in which:

2-. "Figure l is an elevation. partially-in section. Figure 2 is a planview-of the steering-gear-partially in section.

In Figure 1 the steering gear case is indicated generally as I0.Steering column II is mounted upon gear case I!) and encloses steeringshaft I2. Steering shaft I2 terminates at its upper end in threads whichaccommodate nut I3 by which a steering wheel is secured to the shaft.Hour glass worm gear I4 is rigidly secured to the lower end of steeringcolumn shaft I2. This h'our glass worm gear is supported inanti-friction bearings I5. The periphery of hour glass worm gear I4engages rotary follower It. This rotary follower is journaled on shaftI'I through needle bearing I8. The ends of shaft I! are trunnioned insupports mounted on offtake shaft I9. There are, of course, two ofi takeshafts I9 in applicant's steering gear. In Figure 1 only that off takeshaft to the right of steering shaft I2 is shown, Attention is directedto Figure 2 for a clear teaching of the relationship of rotary followerI6 and. off take shaft I9. Steering arms 20 which terminate in eyes 2|are splined to the outer ends of oiftake shafts I9. These offtake shaftsare supported intermediate their ends in bushings 24 mounted in bosses23 (Figure 2). This structure is shown in the sectioned portion ofFigure 1 to the left of the axis of steering shaft l2. A similarmechanism is provided directly opposite that shown and operates theright hand ofitake shaft l9.

Any rotation of the steering wheel causes a correspondin rotation ofhour glass worm gear I 4. This turnin of hour glass Worm gear I 4 causesrotary follower I6 to rotate about the axis of shaft I! on needlebearings I8 and also to revolve about the axis of offtake shaft I9 sincesh'aft I1 is trunnioned on the end of offtake shaft I9. This rotationabout the axis of ofitake shaft I9 is transmitted to the drag links (notshown) through steering arms 20 and eyes 2|.

In Figure 2, a partial section has been taken normal to the steeringcolumn and on a plane passing throu h the axes of both oiftake shaftsI9. This figure shows the intermeshing of hour glass worm gear I4 androtary follower l6. This figure also illustrates adjusting screw 25. Bymeans of this adjusting screw, shaft I9 is movable axially to compensatefor wear of the rotary follower I6 and hour glass worm gear I4. Thisadjusting screw 25 is secured against accidental rotation by star washer26.

The steering gear shown is illustrated in the of the steering; gear 3straight ahead or neutral position. In this position the axes of the twoshafts l1 upon which are mounted rotary followers l6 and the axis ofsteering shaft I2 are parallel and approximately coplanar. The axes ofofftake shafts I9 are parallel but of course are not coincident. In theform illustrated these ofitake shafts I9 are displaced from each otherboth vertically and horizontally, although applicant's inventioncontemahead of and one of which is located behind the steering columnshaft and whose .axes are parallel and fall in a common plane normal tothe steering column shaft, a pair of rotary followers rigidly mountedupon said ofltake shafts and operatively connecting the worm gear andofftake shafts, the axes of said rotary followers falling outside thatplane normal to the offtake shafts and bisecting the hour glass worm asmall but significant distance and adjusting means to move each of saidrotary followers parallel to the axes of the ofitake shafts, saidadjusting means being located on opposite sides of the gear case.

ROY E. FARMER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Wright Aug. 6, 1929 Marles Oct. 18, 1932Murden Mar. 30, 1937 Merce Dec. 26, 1944 Number

